Titration is an analytical laboratory method of determining the molar concentration of an analyte (the solution being identified). During titration, a known concentration of a reactant is prepared and gradually added to the analyte, while carefully measuring the volume, until a reaction threshold is reached.
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What is Titration Used For?
Titration is very useful in the quantitative analysis of the molar concentration of an identified substance, known as an analyte. It involves the gradual addition of a reactant, known as a titrant or titrator, to an analyte until a chemical reaction occurs.
The titration method basically uses a long, graduated burette with a stopcock that can precisely control the flow of the titrant, drop by drop, if necessary. A narrow nozzle or delivery tube is found at the lower end.
A chemical reaction threshold, known as the neutralisation point or the endpoint of titration, is reached when there is a change of colour in the indicator used, such as litmus paper. Several other types of indicators can be used depending on the target range and the type of reactants involved.
But in some cases, chemical indicators aren’t necessary. For example, the reactants themselves may form precipitates when the endpoint is reached. It may also take just one small drop of the reactant to reach the endpoint. Therefore, it’s important that the flow of the titrant is precisely controlled. You can then calculate the concentration of the analyte based on the total volume of titrant you’ve added until the endpoint is reached.
Titration has several practical applications in various fields and industries, though it’s primarily used as a quantitative analytical tool. Here are some examples of its most important uses:
- Environmental management: Environmental scientists use titration to measure the pollutants in rain and snow. They may take samples of rainwater or snow from various locations within a given study area, like a city, and then subject these samples to titration to determine the level of acid formation due to pollution.
- Wastewater analysis and treatment: The types and levels of pollutants in wastewater can be determined using titration methods. Ammonia, for instance, is a basic substance when dissolved in water and is usually the byproduct of decomposition. Therefore, high levels of ammonia in water means that there is a large amount of organic matter in the wastewater.
- Food processing: The nutritional value of processed food and beverages can be adjusted in precise levels using titration. For example, purified orange juice products are subjected to titration to determine the right acidity and amount of ascorbic acid needed for specific demographics, like children.
- Pharmaceutical manufacturing: Titration in the pharmaceutical industry is crucial, since developing and manufacturing certain types of medicines requires precise measurements.
- Biodiesel manufacturing: Even the automotive industry benefits from titration, especially when it comes to the manufacture of biodiesel, where precise pH levels must be maintained for fuel to be useful.
- Wine making: If the pH level of a fermenting batch of wine is off by just a few percent, it can easily become an expensive vinegar! Titration can be utilised here to maintain the right pH levels. Subtle adjustments can also be made to change the flavours.
What is the Method of Titration?
Various types of titrations exist with corresponding indicators. Each type may be used for specific purposes, such as analysing an organic component of a medicine that’s being developed. The scale and complexity vary depending on the purpose.
Here are some examples of the types of titration:
- Acid-base titration: This is the most common method of titration, and it’s one that’s performed by chemistry students in school. It’s also known as neutralisation titration because the main goal is to produce a neutral solution. Depending on the analyte, whether it’s an acid or a base, a corresponding titrant is gradually added until a neutralisation reaction is achieved. Oftentimes, litmus paper is used as an indicator, but there are other types of indicators that can be used based on range and types of reactants.
- Complexion titration: As the name implies, this involves the formation of a substance, which can either be an ion or a neutral molecule from the combination of two simpler substances.
- Precipitation titration: This reaction forms insoluble byproducts that precipitate as solids. One example of this is the titration of a chloride solution with silver nitrate, where silver chloride is formed as a precipitate.
- Redox titration: This determines the concentration of an oxidising agent or a reducing agent. Some analytes don’t require an indicator but can instead act as indicators themselves. One common example of this is the use of potassium permanganate solution as a titrant to determine the concentration of ion (II) ions.
- Weak polyprotic acid titration: ‘Polyprotic’ means multiple protons, an example of which is phosphoric acid, which has the chemical formula H3PO4. Polyprotic acids are weak acids with very small dissociation constants. Depending on the number of protons, there may be multiple equivalence points. Therefore, indicators can change colour multiple times.
What Indicator is Used in Titration?
Various types of indicators are used in titrations, depending on the type of titration, the reactants involved, the range, and the required precision. Some titration methods don’t require indicators because the analytes themselves act as indicators. Here are some examples of indicators:
- Acid-base indicators: These include litmus paper with a pH range of 5.0 to 8.0, where the colour changes from red to blue. Another example is methyl orange with a pH range of 31 to 4.4. Here, the colour changes from red to yellow. Alizarin yellow is for the upper pH ranges of 10.1 to 12.0, where the colour changes from yellow to red.
- Redox indicators: A potentiometer – a type of resistor – is commonly used in redox titrations as an indicator. While a few chemicals will change colours, these types of indicators aren’t very precise.
- Complex-formation indicators: Specialised complexometric indicators, such as iodine, are used for detecting starch complexes and EDTA for metal ion solutions.
What’s the Difference Between Titrant and Titrate?
A titrant is a chemical reagent of known concentration that’s used to find out the concentration of an analyte. Meanwhile, the word titrate is a verb that means to determine the amount of the substance present in a solution using titration methods.
What is an Automatic Titrator?
An automatic titrator is an electronic-mechanical device that can perform titration experiments accurately, precisely, and efficiently. The principles used are the same, but they’re done mechanically with the help of computers. The results can automatically be displayed without the need for complex calculations. The machine does the entire work automatically using potentiometric sensors.
